The invention relates to a computer-controlled, modular microscopy system that produces a magnified video image of a specimen of interest. The positions of all moving parts of the microscope are controlled from a computer.
The invention also relates to an optical system for use with a video camera, where the optical system magnifies an image to be recorded by the camera.
Microscopes are conventionally-used optical instruments in a variety of fields where workers need clear images of structures too small to be seen by the naked eye. For example, medical professionals, biologists, and cytologists conventionally use microscopes to observe cell cultures or uni- or multicellular organisms, while electronics specialists conventionally use microscopes to study silicon wafers.
State-of-the-art microscopes consist of several assemblies that are attached to provide a functioning system. The major assemblies are the stand, a stage adapted to hold a sample, a lens turret having one or more objective lenses, an observation tube having one or two ocular lenses, and a means of illuminating a sample. The objective lens magnifies an image of the sample; the magnified image is then directed into the observation tube.
The foundation for a conventional microscopy system is the stand, which typically accounts for about 25% of the system price. The stand provides a stationary platform to hold the imaging and illumination optics. The stage is typically attached to the stand using a rack-and-pinion structure. This allows the stage to travel vertically toward the objective lens, or away from the objective lens, so as to focus the sample image seen through the observation tube.
The stage and observation tube may be arranged in either of two ways. In an upright microscope, the stage is positioned beneath the observation tube, with the objective lens being directed toward the sample. In an inverted microscope, the stage is positioned above the observation tube, with the objective lens being directed toward the sample. Whether the microscope is upright or inverted, the sample may be illuminated by transmitted fight or by incident. In a transmitted light illumination system, a beam of light bearing an image of the sample is produced by shining a beam of light through the sample. In a incident light system, a beam of light bearing an image of the sample is produced by reflecting a beam of light off of the sample.
In addition to the above-described components, accessory assemblies such as still or video cameras, filters, or polarizers may be added to the microscope. Cameras are particularly useful accessories, as they allow a researcher to record an image for later study. However, most microscopes are designed to permit viewing of an image by the human eye, forcing the researcher to set up a special apparatus to support the camera above the ocular lens, and then carefully focus the image onto the imaging plane of the camera.
It is also known to control the distance between the microscope stage and the objective lens by computer, so as to provide automatic focus. For example, if the computer determines that the distance between the microscope stage and the objective lens is incorrect for the objective lens, the computer can send a signal to a motor which moves the stage toward or away from the objective lens. The microscope may have a mechanism for movably supporting a plurality of objective lenses so that one objective lens having a defined magnification is in the path of a light beam at any given time. If a lens having the wrong magnification is in the optical path, a signal is sent from the computer to a motor which causes the lens-supporting mechanism to move the incorrect lens out of the optical path, and move a lens having the desired magnification into the optical path. Typically, the lens supporting mechanism is a revolving device which rotates about an axis which is coaxial with the axis of the observation tube. The objective lenses are directed at an angle relative to this axis, so that each may be rotated into the path of the incoming light beam. As a result, the light beam, after it passes through the objective lens and before it enters the observation tube, must be bent using a system of mirrors or prisms. This requirement for additional precision optical components adds to the expense and complexity of the system. It is therefore desirable to create a microscope having a means for exchanging microscope objective lenses under computer control which does not require the use of optics to bend the incoming light beam.
Additionally, people that use optical microscopes have long been asking microscope designers to make microscopes more suitable for human use. The typical microscopist sits hunched over on a laboratory stool, peering downward through the ocular lens of his microscope, in a position guaranteed to cause severe back pain, neck pain, and/or eye strain. In fact, K. S. Lee and L. A. Humphreys, at the 29th Annual Meeting of the Proceedings of the Human Factors Society, reported that 84% of microscopists had job-related musculoskeletal pain. This forces many or most microscopists to leave the profession in considerably under ten years. In many cases, back or neck surgery is necessary to relieve job-related pain sufficiently to allow the microscopist to lead a normal life.
It has been suggested that this sorry statistic could be greatly reduced by using microscopes that display images on computer monitors. Additionally, conventional bench microscopes are designed so that handicapped people or people confined to wheelchairs have trouble reaching the eyepiece, making it difficult for them to pursue careers in microscopy. It is necessary to develop microscopes that can readily be used by the disabled. Microscopes that display images on computer monitors can be used in this way.
The invention is directed to a computer-controlled microscopy system, featuring a stage for supporting a sample; a means for directing a vertical beam of light through the sample; a means for observing an image carried by the beam of light; and an optical system. The optical system includes:
i) a plurality of light-transmitting objective lenses arranged in a linear array on a first plate, including at least a first objective lens positioned in the path of the vertical beam of light and a second objective lens not positioned in the path of the vertical beam of light; and
ii) a lens system adapted to receive the vertical beam of light after it has been transmitted through the first objective lens and focus the vertical beam of light onto the imaging plane of the video camera.
A second plate which is rigidly connected with the lens system is slidably fixed to the first plate by means of linear bearings, allowing the first plate to move along the second plate until the first objective lens moves out of the path of the vertical beam of light and the second objective lens moves into the path of the vertical beam of light. The first plate may be caused to move along the second plate until the first objective lens moves out of the path of the vertical beam of light and the second objective lens moves into the path of the vertical beam of light. Exchange of objective lenses in this fashion is normally carried out under computer control.
The technology used in this invention is similar to that used in the microscope described in U.S. Pat. No. 5,818,637, the entire disclosure of which is incorporated herein by reference.